The absence of bees matters, because they’re the most important pollinator for many crops, as they carry pollen from one flower to another. Without bees we wouldn’t have apples, almonds, berries and melons. Bees are particularly important in Yolo County where they’re needed to grow seed crops such as sunflower and carrot seed, worth more than $10 million in 2003.

The European honeybee, with its yellow and blacked striped abdomen, is only one of about 4,000 bee species in the United States. Unlike honeybees, which live in colonies called hives, most native bees are solitary or individual nesters.

The females nest by themselves in the ground, in hollow stems of plants, or in holes in wood or dead trees, often made by other critters. Each female solitary bee lays one or more eggs in each nest she builds. She also stashes pollen and nectar in each nest for the bee larvae to eat when they hatch.

Some of their common names reflect the way they build nests: leafcutter bees, digger bees and carpenter bees. Bumblebees, with their distinctive fuzzy appearance, are social.

They nest in colonies, favoring enclosed places such as the hollows of trees or abandoned rodent burrows.

As a result of their nesting habits, native bees are often vulnerable to disturbance and their numbers have been declining. Mace Vaughn, conservation director for the Xerces Society, a Portland group dedicated to saving insect pollinators, says, “Native bees are in trouble.”

This could be a problem for farmers who rely on bees for pollination. Honeybees are not as efficient at gathering and moving pollen around in crops as native bees such as bumblebees. In addition, honeybees are in short supply due to various diseases and mites that have been killing hives. “As a result hives are expensive to rent due to their high demand and limited supply,” says almond breeder Mark Kochi. “Some growers spent up to $100 per hive this year for almond pollination, which is more than double the usual price.”

Building homes for solitary bees can be as simple as clearing a patch of ground and leaving it undisturbed, putting a bundle of hollow twigs on a fence or drilling holes in a block of wood.
One indication that nesting sites are in short supply is the popularity of nest sites. “We find that if we put out nesting boxes, they are filled almost immediately,” said Vaughn. “That indicates there’s a need.”

Planting a variety of plants that flower throughout the growing season is also important for native bees. Native bees also need a refuge from insecticides. “All of these resources can occur in small patches or in marginal areas of a farm, such as in hedgerows of trees or shrubs planted around fields.” said Vaughn.

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Photo: Rusty patched bumble bee by Johanna James Heinz.